<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>AJAX POST 请求</title>
    <style>
        #result {
            width: 200px;
            height: 100px;
            border: solid 1px red;
        }
    </style>
</head>

<body>
    <div id="result"></div>
    <script>
        //获取元素对象
        const result = document.getElementById("result");
        //绑定事件
        // addEventListener 添加事件监听
        // mouseover 当鼠标移至
        result.addEventListener("mouseover", function() {
            //1、创建对象
            const xhr = new XMLHttpRequest();
            //2、初始化 设置类型与URL
            xhr.open('POST', 'http://127.0.0.1:8000/server');
            //设置请求头
            xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
                //3、发送
                //xhr.send('a=100&b=200&c=300');
                //xhr.send('a:100&b:200&c:300');
            xhr.send('12384464984');
            //4、事件绑定
            xhr.onreadystatechange = function() {
                //判断
                if (xhr.readyState === 4) {
                    if (xhr.status >= 200 && xhr.status < 300) {
                        //处理服务端返回的结果
                        result.innerHTML = xhr.response;
                    }
                }
            }
        });
    </script>
</body>

</html>